After you install Service Pack 1 (SP1) for Windows XP, your computer may drop virtual private network (VPN) connections that are using Point-to-Point Tunneling Protocol (PPTP) after about 55 seconds.
This behavior may occur if Internet Connection Sharing is turned on for one or more of your network connections.
Service pack information
To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
322389 How to obtain the latest Windows XP service pack
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language. The English version of this fix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
Date Time Version Size File name ------------------------------------------------------------ 14-Nov-2002 14:16 5.1.2600.1142 154,112 Netman.dll 14-Nov-2002 14:16 5.1.2600.1142 435,200 Ipnathlp.dll
To work around this problem, turn off Internet Connection Sharing to prevent VPN connections from disconnecting. To do this:
Open Network Connections.
Right-click the dial-up connection, local area network connection, PPPoE connection, or VPN connection that you no longer want to share, and then click Properties.
Click the Advanced tab.
Clear the Allow other network users to connect through this computer's Internet connection check box, and then click OK.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Microsoft Windows XP Service Pack 2.